1. Field of the Invention
This invention relates to the commercial application of flammable organic polymer matrix composites where fire is of concern to workers and passengers in industry, transportation, military, petroleum, powerhouse and aircraft.
2. Description of the Related Art
The current use of flammable organic polymer matrix fiber-reinforced composites in the manufacture of aircraft interiors (e.g., phenolic polymers) and structural applications (e.g., epoxy polymers) limits passenger safety where fire hazard is an important design consideration. In-flight fire is ranked as the fourth highest known contributing cause of fatalities arising from accidents involving commercial jet aircraft (Ref. 1). The Federal Aviation Administration (FAA) believes that if aircraft accident rates continue at a constant rate, then death due to fire will increase at 4% per annum in-line with the growth in air passenger traffic (Ref. 2). This condition becomes even more hazardous with the planned commercial development of multi-tier 600 passenger aircraft.
Prior art in silicone resin development demonstrated ten years ago (Ref. 3) the development of essentially non-burning methyl silicone resin composite materials for use in aircraft cabin interiors. Even in the absence of halogenated or other fire retardants, the fire performance was superior to the phenolic resins currently used in aircraft interiors. Also, the heat release, CO and smoke yield of the developed methyl silicone resins were demonstrated as superior to phenolic resins (Ref. 3).
The Beckley patent, U.S. Pat. No. 5,552,466 is specific to teach methods of producing processable resin blends that produce high density silica ceramics in the red heat (600 to 1000° C.) zone. The preferred catalyst, zinc hexanoic acid produces a high cross-link density polymer by the Beckley methods of processing that favor the formation of high yield ceramic composites compared the high temperature elastic silicone polymers produced by the Clarke methods of using boron nitride, silica and a preferred boron oxide catalyst. No mention is made of compression-recovery properties common to Clarke related composites.
The Chao, Sarmah, Burns and Katsoulis, Non-Burning Silicone Resin Composite Laminates Central R&D, Dow Corning Corporation, Midland Mich. 48686, 7-14-99 paper refers to silanol-silanol condensation cured methyl silicone resins enabling the fabrication of non-burning composites with lower CO and smoke yields than laminates made with organic laminates. The paper also reveals in FIGS. 1 to 4 that the methyl silicone resin and composites made therefrom were superior in fire resistant performance to phenolic resin and composites commonly used in aircraft interiors. No mention is made of producing a high temperature elastic methyl and or phenyl silicone resin containing boron nitride, silica and boron oxide to produce an elastic fire resistant silicone laminate that slowly transforms into a flexible ceramic fire barrier then ceramic with 80 to 100% strength retention and instant self extinguishing capability after FAA Fire Penetration testing (FAR 25.853) at 20000 F for 15 minutes with greater endurance capability.
The Boisvert, et al patent, U.S. Pat. No. 5,972,512 is specific to teach silanol-silanol condensation cured methylsilsesquioxane resins enabling the fabrication of non-burning composites with superior performance than organic laminates. No mention is made of producing a high temperature elastic silicone containing boron nitride, silica and boron oxide to produce an elastic fire protective silicone laminate that slowly transforms into a flexible ceramic then ceramic with no burn through at 20000 F after 15 minutes. Also, the fire resistance is specific to methyl resins overlooking the high thermal advantages of phenyl resins even when used sparingly. Also, elastic composites have dissimilar materials joining advantages not mentioned in the Boisvert patent.
The Clarke patent, U.S. Pat. No. 6,093,763 is specific to teach the use of the zinc hexanoic acid catalyst for a specific ratio of 2:1 for two specific silicon resins with boron nitride as filler. The zinc hexanoic acid catalyst produces a different high cross-link density polymer than the preferred elastic composite produced from a reaction mixture of boron nitride, silica and boron oxide and controlled reaction methods. The amount of zinc catalyst required to enable the sealant to perform is also excessive in comparison to the boron oxide catalyst which is sparingly used to favor a slow reaction for producing elastic composites.
The Clarke patent, U.S. Pat. No. 6,161,520 is specific to teach that the gasket materials derived from Clarke's copending U.S. patent application Ser. Nos. 08/962,782; 08/962,783 and 09/185,282, all disclose the use of boron nitride as the catalyst for condensation polymerization of the resin blend needed to produce the gaskets. However, boron nitride is not a catalyst as incorrectly disclosed therein. The certainty that boron nitride is not a catalyst has been shown by attempting to repeat the Clarke U.S. Pat. No. 6,183,873 patent's FIG. 1 “gel” curve at 177° C. using the preferred CERAC, Inc. item #B-1084-99.5% pure boron nitride. Other research associates have also confirmed the certainty that boron nitride is not a silicone condensation catalyst. Numerous possible contaminates would need to be investigated to find the actual catalyst or combination of catalysts including the possibility of humidity. No prior mention has been made of using boron nitride, silica and boron oxide as a reaction mixture processed in a rotating cylinder at ambient temperature to favor the production of a high temperature elastic composite. Neither is boron oxide mentioned as catalyst with boron nitride cost advantage addressed when boron oxide is used as a residual from the chemical processing (Ref. 5, 6) of boron nitride.
The Clarke patent, U.S. Pat. No. 6,183,873 B1 is specific to teach the use of boron nitride as the catalyst in producing polysiloxane resin formulations for hot melt or wet impregnation of ceramic reinforcements. As stated above, boron nitride is not a catalyst as incorrectly claimed. The more costly and toxic hot melt and wet processing methods of the '873 patent are eliminated with the superior ambient temperature methods now addressed by the inventor. No resin formulations using boron oxide as the catalyst (see Table 6 of Clarke application no. 1) are mentioned. Additionally, the methods of producing “flexible ceramic” high temperature elastic laminates are not addressed. Also, the use of laser processing (up to 16,5000 C) to increase the tensile strength by 25% and form ceramic sealed edges eliminating the need for costly end closures is not addressed. The boron nitride cost savings in reducing the boron oxide leaching operations in the commercial production of boron nitride and fire resistant advantage of using residual boron oxide contained in boron nitride as a source for the catalyst addition are not mentioned.
The Clarke SAE 2002-01-0332 paper (Ref. 7) refers to high purity boron oxide as a Lewis acid catalyst with silica mentioned as an unobvious inhibitor for these silicone condensation polymerization catalysts. High cost boron nitride and boron oxide are added separately. No mention is made of producing resin formulations using boron nitride containing boron oxide residues as a source of boron oxide catalyst and cost savings advantage. Additionally, the methods of producing “flexible-ceramic” laminates capable of high-temperature elastic recovery (FIG. 1 of Clarke application no. 1) are not addressed. Also, the use of laser processing (up to 16,500 C) to increase the tensile strength by up to 25% and forming ceramic sealed edges is not addressed. The “self extinguishing” property of the elastic composite when heat is removed is also not mentioned. This is an essential requirement to prevent combustion pre-ignition in superior fuel saving flexible ceramic composite ignition devices.